Case 2: Three stereoscopic displays

An exhibition by Peter Morse titled "Antarctica Virtua" at the John Curtin Gallery, Curtin University, Perth, February to March 2007. This exhibition consisted of a total of 5 stereoscopic displays but the main work comprised of 3 stereo displays side by side and each approximately 2.5m wide.

Each screen is driven from one Mac with a Matrox DualHead2Go card, although this wasn't strictly necessary for the G5. The 2048x768 canvas supplied by the Matrox card has the left eye image on the left (1024x768) and the right eye image on the right half. As such each frame of the QuickTime movie is made up of the left and right eye side by side.

• What is it that causes the huge performance drop as soon as movies hit the 2048 pixel wide bound? For example, at 2046 they easily play at the desired 25fps, at 2048 they play at a few frames per second!

• It would have been advantageous to run the three wall display from a single computer. This would have allowed more scope for relating the content between the displays. At what stage will the hardware be capable of this? [Note that Quartz Composer that ships with Developer tools 3.X and Leopard has this functionality, namely network based communication between machines, see case study 8].

• Why can't the iMac display be turned off or disabled? This seriously limits it's usefulness for many exhibition projects where only the projected display is required. In the case of many dark environments such as planetariums, the light from the display is an issue.

• What exactly happens on a iMac in mirror mode when the external display is at a higher resolution than the internal display? Is everything drawn twice or is one display a scaled version of the other?

Photos

Hardware

Combination of Mac Pro and 24" iMacs, each with a Matrox DualHead2Go box.